Pressure drop characteristics of cryogenic mixed refrigerant at macro and micro channel heat exchangers

Abstract

Mixed Refrigerant-Joule Thomson (MR-JT) refrigerator is widely applied in various kinds of cryogenic system these days. Temperature glide effect is one of the major features of using mixed refrigerant since a recuperative heat exchagner in MR-JT refrigerator is utilized for mostly two-phase flow. Although pressure drop esitimation of multi-phase and multi-component fluid in cryogenic temperature range is necessarily required in MR-JT refrigerator heat exchanger designs, it has been rarely discussed so far. In this paper, macro heat exchanger and micro heat exchanger are compared to investigate the pressure drop characteristics in the experimental MR-JT refriegerator operations. Tube in tube heat exchanger (TTHE) is a well-known macro-channel heat exchanger in MR-JT refrigeration. Printed Circuit Heat Exchanger (PCHE) has been developed as a compact heat exchanger with micro size channels. Several two-phase pressure drop correlations are exmained to discuss the experimental pressure measurement results. The result of this paper shows that cryogenic mixed refrigerant pressure drop can be estimated with conventional two-phase pressure drop correlations if appropriate flow conditions are identified.